Sonochemical degradation of CCl4 in alcohol-water system

In this study, methanol (MeOH), ethanol (EtOH), 1-propanol (PrOH), and ethylene glycol (EG) were used as alcohol-CCl₄ pretreatment solutions for the first time to investigate the effect of alcohol on the sonochemical degradation of CCl₄. The results showed that this pretreatment method provided the homogeneous dissolution of CCl₄ in aqueous solution in a short preparation time and the enhancement of the sonochemical degradation of CCl₄. In addition, the rate of the degradation of CCl₄ related to the hydrophobicity of the added alcohol. It was considered that high hydrophobic alcohol molecules accumulated at the interface region of cavitation bubbles contributed to the scavenging of •OH radicals produced by sonolysis of water and to the pyrolysis itself, resulting in the production of a large amount of •H radicals. The formation of •H radical and its secondary products, such as H₂ could lead to the reductive degradation of CCl₄. In previous studies, the addition of alcohol has been observed only as a negative effect on the sonochemical degradation of organic compounds such as the reduction of bubble temperature, and the quenching of the oxidative degradation by scavenging •OH radicals. However, our results indicated that the positive effects of alcohol on the sonochemical degradation of CCl₄ were more significant than the negative effects.